So, after about 4 weeks of work I have my perfectly working 2 channel β22 amp by Ti from AMB labs. “Here’s what happened”(Monk)

First, I had to make a list of the required parts and from the corresponding supplier. I needed parts for 4 β22 and 2 σ22 boards(power supply). THat is how my BOM spreadsheet was born: β22 BOM (Numbers и Excel формат). It took me the better part of two days to put this together and make it smarter enough to produce EZ Import lists for mouser and digikey. Of course it had a lot of errors initially and it wasn’t until finished my amp that I had everything corrected. So one day I had this at home:

I setup my working space on half of the dining table. That was occupied for the next 4 weeks 🙂

And the populating started. I forgot to write that the boards, mosfets and jfets are from amb.org as well as the Alps RK27112A pot that I use.

I tried to follow the rule of height going from shortest to tallest component. That way it was easy to flip the board and do the soldering. I also worked on the 2 sigmas first and then the 4 betas at the same time.

First came the sigmas:

And of course the resistors were first. Since there were many of the same type I first grouped them

Bent the legs

And solder at the end:

I repeated the same until all resistors were in place

Then the diodes. To be honest they are shorter than the 1/8W resitors but not by much, so it was ok.

Then I did the big resistors and little caps:

The transistors were next.

This is the place where I had to place the wimp caps but it turned out I ordered the wrong caps (first error in my spreadsheet). At this point I decided to finish the rest of the components leaving the wimp caps and the MOSFETs for last:

And that was the easy part. Next were the 4 β22 boards! Some components call for 20-30 count! That’s a lot of ‘stuff’…

I followed the same rule again but this time I decided to put all resistors on first before I solder them:

After everything was in place, it was 35 resistors * 2 pins * 4 boards of soldering points:

At this point I started to pile up on jumpers 🙂

Then i did the other short components:


Next were the BJTs. 16 per board (6 PNP and 6 NPN):

JFETS in pairs by amb.org again. This time these had special positioning, not per the silkscreen. I’m still not sure why he didn’t fix that in his 1.02 board but anyways it was fun 🙂

The trimpots, which obviously are reversed (which I will figure out at the end when I’m trying to tune the amp:

The red wimps and the bigger panasonics:

At this point I had all boards populated except for the MOSFETs and their heatsinks. For the heatsinks I used my trusty Arctic Silver 5, which I’ve been using for my CPUs all the time without problems:

Here is how they look like finished:

I forgot to mention that I made 3 epsilon 24 boards for the Bulgin push buttons, again by amb.org:


Now was time for a smoke test for the PSU. I wired up the transformer, the power relay, the epsilon board and the Bulgin button. First few tries were not successful because I had the transformer wired wrong. But eventually I got it right and I had stable ±29.89V out from the sigma board (configured for 30V) I even installed a thermal breaker on one of the heatsinks just in case, since I was planning to drive my small speakers with it too.


O yes, I also decided to make my own case. After some cutting and lots of sanding I got enough parts for two cases:

And since I was going for the two case wiring, I had to make an umbilical cable with 3 wires for power and 4 wires for the power switch (I wanted the switch to be on the amp case, not the power case). So it was time for the 7x18AWG umbilical:



Umbilical or not, I had to test and tune the amp 🙂 Here is where I found out my trimpots are positioned in reverse. Few mods later I had my two working boards ready to drive speakers or headphones:

Now that I had half the work done, was time to do the cases + panels + painting + wiring… SInce I used thin wood from Michaels it was easy to cut but hard to glue correctly. I also don’t have any precision power tools so the results were OK. I used whie primer and a silver paint on top. THe idea was to have some openings on the top for the heat to go out:

First was the amp. It was tight, and I even had to cut the Switchcraft plug, but in the end all was in place:


I got a wire divider for the kitchen from BBB for my wire mesh:

At this point I alms had forgotten that I had to do the PSU case as well…


I placed everything in, placed the top on and that was it:

Last step was to connect the speakers, umbilical, power cord and press that nice Bulgin button:

It was quite an experience but it was well worth it. I learned quite a lot (like spend the extra bucks and get a nice case and machined panels, which is what I might do anyway). In the end the amp sounds great. It is an awesome overkill for headphones and can drive my uFonkens without a problem. I think that would be my DIYing for a while. It s time to start listening to some music 🙂

You can find all pics in my gallery

A big thank you to Ti for the great design and everyone on head-fi that helped.